The present invention relates generally to scramjet engines and more particularly to a fuel injector for a hypersonic flight vehicle scramjet engine.
At hypersonic Mach numbers (i.e., greater than Mach 5) a flight vehicle having an air breathing engine, such as a scramjet, requires an engine combustion chamber (also known as a combustor) having a large frontal cross-sectional area. In scramjet engine design, it is important to distribute the fuel, such as pressurized hydrogen gas, uniformly over this area for proper combustion. It is noted that injecting the fuel into the combustor itself provides thrust apart from the thrust created by the fuel combustion. In commonly assigned and copending U.S. patent application Ser. No. 828,844 entitled "Ramjet/Scramjet Engine" by DANIEL J. Lahti et al., filed Jan. 2, 1986, there is shown a scramjet engine having an array of horizontally-spaced fuel injectors each with a wedge shape wherein the fuel exits a single convergent-divergent fuel outlet nozzle (a single-wall-slot fuel injector) into the combustor. Combustor design is always concerned with proper mixing of the fuel and the inlet air for uniform combustion. As the engine inlet compresses (and therefor heats) the incoming air and as the incoming air impinges upon the fuel injector at hypersonic speeds (and therefor frictionally heats the fuel injector), there also is the problem of cooling the fuel injector so as to prolong component life and/or allow the use of materials that would fail without cooling.